INJECTION MOLDING APPARATUS HAVING MELT DIVIDING BUSHINGS

摘要

Multi-layer injection molding apparatus having integral multi-layer melt dividing bushings seated in the melt distribution manifold for dividing a first melt passage extending to annular melt channels in heated nozzles. Matching melt channels machined in the front face of the first layer and the rear face of the second layer of each melt dividing bushing form a melt conduit which branches from an inlet to two spaced holes extending through the second layer. A pair of matching melt channels machined in the front face of the second layer and the rear face of the third layer of each melt dividing bushing form two melt conduits, each of which branch from one of the holes through the second layer to two of four spaced holes through the third layer. The four holes through the third layer align with four melt bores leading to the annular melt channel in one of the heated nozzles. A second melt passage may extend through a central bore in each melt dividing bushing to a central melt channel in the heated nozzle. In another embodiment, the first melt passage also extends through central holes in the second and third layers of the melt dividing bushing to a central melt channel in the heated nozzle. In this case, the second melt passage may extend through a melt bore through the melt dividing bushing or may similarly divide into two in a melt conduit extending between two of the layers of the melt dividing bushing.